Re: Using "Sum" (i = 1 ... N) in a function definition
- To: mathgroup at smc.vnet.net
- Subject: [mg49709] Re: [mg49666] Using "Sum" (i = 1 ... N) in a function definition
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Thu, 29 Jul 2004 07:43:26 -0400 (EDT)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <200407271100.HAA11129@smc.vnet.net>
- Reply-to: murray at math.umass.edu
- Sender: owner-wri-mathgroup at wolfram.com
MyFunc[i_] := Fold[Plus, 0, Take[MyData, i]] Rainer wrote: > I was trying to define a function using the Sum command in the > following way (simplified example): > > MyData = {3,2,4,5,6}; > MyFunc[i_] = Sum[MyData[[j]],{j,1,i}]; > > As you can see, the idea is to use the length of the list (i) > as a variable in the function definition, such that > > MyFunc[1] = 3 > MyFunc[2] = 3 + 2 = 5 > MyFunc[3] = 3 + 2 + 4 = 9 > > etc. Mathematica does not like the abobe statements, and prints the > following error message: > > "Part specification K$394 is neither an integer nor a list of > integers." > > Does anybody know how to define (correctly) such a function. Should be > possible ...? > Thanks > Rainer > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- Using "Sum" (i = 1 ... N) in a function definition
- From: wilhelm.rainer@gmx.net (Rainer)
- Using "Sum" (i = 1 ... N) in a function definition